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V Larson

Publications and source records attributed to V Larson.

12 recordsLinked to original sources
PubMed1999

Thermodynamics and kinetics of ligand-protein binding studied with the weighted histogram analysis method and simulated annealing.

The thermodynamics of ligand-protein molecular recognition is investigated by the energy landscape approach for two systems: methotrexate(MTX)--dihydrofolate reductase(DHFR) and biotin-streptavidin. The temperature-dependent binding free energy profile is determined using the weighted histogram analysis method. Two different force fields are employed in this study: a simplified model of ligand-protein interactions and the AMBER force field with a soft core smoothing component, used to soften the repulsive part of the potential. The results of multiple docking simulations are rationalized from the shape of the binding free energy profile that characterizes the thermodynamics of the binding process.

Biotin↗
PubMed1996

Salivary duct determination in Drosophila: roles of the EGF receptor signalling pathway and the transcription factors fork head and trachealess.

Organogenesis in Drosophila embryos begins at 4-5 hours of development as the expression of organ-specific genes is initiated. The salivary primordium, which occupies the ventral epidermis of parasegment 2, is among the earliest to be defined. It is soon divided into two distinct regions: the more dorsal pregland cells and the more ventral preduct cells. We show that it is the opposing activities of the Drosophila EGF receptor (DER) signaling pathway and the Fork head transcription factor that distinguish these cell types and set up the boundary between them. DER signaling acts ventrally to block fork head expression in the preduct cells, thereby restricting gland identity to the more dorsal cells. Fork head in turn blocks expression of duct-specific genes in the pregland cells, thereby restricting duct identity to the more ventral cells. A third regulatory activity, the Trachealess transcription factor, is also required to establish the identity of the preduct cells, but we show that it acts independently or downstream from the DER:fork head confrontation. In trachealess mutants, subdivision of the salivary primordium occurs normally and the dorsal cells form glands, but the ventral cells are undetermined. We present a model proposing that trachealess is the crucial duct-specific gene that Fork head represses to distinguish pregland from preduct cells.

Animals↗
PubMed1992

Effect of intensive endurance training on lipoprotein profiles in young and older men.

Although there are considerable data concerning the effects of endurance exercise training (ET) on plasma lipoproteins, the results have been quite inconsistent. The observed variability of response may be related to the age, sex, adiposity, or diet of the subjects tested, or to the type and intensity of the exercise intervention. Furthermore, there is relatively little such data in older individuals. Therefore, in the present study, we investigated the effects of intensive ET on lipoprotein profiles in healthy young (n = 12; 28.2 +/- 2.4 years) and older (n = 15; 67.5 +/- 5.8 years) men. Unlike subjects in most similar studies, our subjects were weight-stabilized on a constant-composition diet for 21 days prior to determination of the lipoprotein profile before and after the ET program. At baseline, the two groups were not significantly different with respect to any individual component of their lipoprotein profiles, relative weight, or percent body fat, but the older men had a more central distribution of fat by both waist to hip ratio (WHR) and computed tomography (CT). Maximal aerobic power, expressed per kilogram of body weight (VO2 max), was 33% lower (P less than .001) in the older men at baseline. Following the 6-month, walk/jog/bike ET program (5 d/wk), both the young (+18%, P less than .001) and the older (+22%, P less than .001) men increased their VO2 max. This was associated with small, but significant, decrements in weight, percent body fat, and WHR only in the older men.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The effect of intensive endurance exercise training on body fat distribution in young and older men.

Little is known about the effects of exercise interventions on the distribution of central and/or intra-abdominal (IA) fat, and until now there were no studies in the elderly. Therefore, in this study we investigated the effects of an intensive 6-month endurance training program on overall body composition (hydrostatic weighing), fat distribution (body circumferences), and specific fat depots (computed tomography [CT]), in healthy young (n = 13; age, 28.2 +/- 2.4 years) and older (n = 15; age, 67.5 +/- 5.8 years) men. At baseline, overall body composition was similar in the two groups, except for a 9% smaller fat free mass in the older men (P less than .05). The thigh and arm circumferences were smaller (P = .001 and P less than .05, respectively), while the waist to hip ratio (WHR) was slightly greater in the older men (0.92 +/- 0.04 v 0.97 +/- 0.04, P less than .01). Compared with the relatively small baseline differences in body composition and circumferences, CT showed the older men to have a twofold greater IA fat depot (P less than .001), 48% less thigh subcutaneous (SC) fat (P less than .01), and 21% less thigh muscle mass (P less than .001). Following endurance (jog/bike) training, both the young (+18%, P less than .001) and the older men (+22%, P less than .001) significantly increased their maximal aerobic power (VO2max). This was associated with small but significant decrements in weight, percent body fat, and fat mass (all P less than .001) only in the older men.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1989

Protective effect of a synthetic peptide comprising the complete preS2 region of the hepatitis B virus surface protein.

A peptide was synthesized containing the entire 55 amino acid residue sequence of the hepatitis B virus (HBV) surface antigen preS2 region (ad subtype). The unconjugated peptide was inoculated into four chimpanzees. Following multiple injections, all of the animals developed specific antipeptide antibodies that reacted with intact surface antigen particles bearing the preS2 moiety. All four peptide-inoculated animals were found to be protected from infection after intravenous challenge with live HBV of either the ad or ay subtypes.

Animals↗
PubMed1984

Intracoronary streptokinase therapy in the coronary care unit for acute myocardial infarction.

Intracoronary streptokinase was offered and preliminary coronary angiography performed in 14 patients who were seen with the clinical diagnosis of acute myocardial infarction within 4 h of onset of symptoms. The procedure was performed in the Coronary Care Unit (CCU) of St. Peter's Medical Center with the use of a portable C-arm fluoroscope. Angiography was recorded on video tape. Service was provided by an "on-call" team consisting of two physicians, a CCU nurse, and a radiology technician, on a 24-h service basis. Adequate visualization of coronary anatomy was obtained in all patients. Patency of occluded vessels was achieved in 10 of 11 patients who received intracoronary streptokinase. The initial streptokinase bolus was administered at a mean interval of 4.1 h from onset of symptoms. It is concluded that speedy and effective coronary thrombolytic therapy can be provided in the CCU on a 24-h service basis by an on-call team. The use of CCU for this purpose will make this therapy widely available across the country, without the need for Cardiac Catheterization Laboratory.

Adult↗
PubMed1981

Blood concentrations of beta hydroxybutyrate in clinically normal Holstein-Friesian herds and in those with a high prevalence of clinical ketosis.

Statistical parameters necessary for the comparison of herd blood beta hydroxybutyrate (HB) concentration means with HB concentrations in the general population were determined in 11 clinically normal herds of Holstein-Friesian cows. These parameters were then used to compare clinically normal cows from 2 Holstein-Friesian herds experiencing a high prevalence of clinical ketosis with the normal population. Blood HB concentration means were compared with plasma glucose concentration means for their relative value as predictors of clinical ketosis prevalence within a herd. Blood HB concentration values were distributed approximately log normal and were directly related to amount of milk production. Herds with a high prevalence of clinical ketosis had blood HB log means higher (P less than 0.01) and glucose means lower (P less than 0.05) than did the normal population. Herd blood HB log means should be determined on 7 or more animals within specified production groups. When these means exceed the normal population log mean by more than 1 SD, susceptible cows in the herd may be at increased risk for the development of clinical ketosis. Blood HB log means may be of greater value than are plasma glucose concentration means for the prediction of herd ketosis prevalence.

3-Hydroxybutyric Acid↗
PubMed1981

Influence of ration composition and energy balance on blood beta-hydroxybutyrate (ketone) and plasma glucose concentrations of dairy cows in early lactation.

The effect of ration composition, with respect to concentrate, crude protein, and methionine hydroxyanalog content, on blood beta-hydroxybutyrate and plasma glucose concentrations was assessed in Holstein cows every 2 weeks over the first 6 weeks of lactation. The correlation of these metabolites with estimated energy balance, and the effects of these ration variables on this correlation were studied. High concentrate diets (60% of dry matter) compared with low concentrate diets (40% of dry matter) increased mean plasma glucose values and reduced mean blood beta-hydroxybutyrate concentration. Variation in crude protein and methionine hydroxyanalog supplementation did not affect metabolite concentration. The correlations between blood beta-hydroxybutyrate and energy balance and between plasma glucose and energy balance were weak and subject to the influence of variation in ration composition. It was concluded that plasma glucose and blood beta-hydroxybutyrate concentrations cannot be used as valid indicators of energy balance. However, it did appear that blood beta-hydroxybutyrate might be used as an indicator of the relative glucogenic potential of dairy rations and that blood concentrations of this metabolite could potentially be used to adjust factors in the ration which influence glucose availability to the cow.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

Prostatic duct carcinoma: exfoliative cytology.

The cytologic findings in voided urine specimens from prostatic duct carcinoma are presented. Neoplastic cells from these unusual tumors were identified as well as the occasional red blood cell and histiocyte. The adenocarcinoma cells features irregular nuclei and their cytoplasm was occupied almost entirely by large secretory vacuoles. The differential diagnosis of this tumor from some other neoplasms and its association with transitional cell carcinoma as well as its histogenesis are discussed.

Adenocarcinoma↗